Effect of 3{ital d} ion substitution in the {ital R}Ba{sub 2}Cu{sub 3{minus}{ital x}}{ital M}{sub {ital x}}O{sub 7} ({ital R}=Sm, Dy; {ital M}=Fe, Ni and Zn) system: Implications of {ital R} ion dependence and disorder
- Materials Science Research Centre, Indian Institute of Technology, Madras 600036 (India)
Systematic studies on the {ital R}Ba{sub 2}Cu{sub 3{minus}{ital x}}{ital M}{sub {ital x}}O{sub 7} ({ital R}=Sm, Dy; {ital M}=Fe, Ni, Zn) system were carried out in order to determine the effect of the rare-earth ionic size and magnetic moment on the {ital T}{sub {ital c}} suppression rate. The phases were characterized by powder x-ray diffraction (XRD), resistivity, and ac susceptibility measurements. XRD studies indicate a higher solubility limit of {ital M} ions in the SmBa{sub 2}Cu{sub 3{minus}{ital x}}{ital M}{sub {ital x}}O{sub 7} [Sm-123({ital M})] system as compared to the DyBa{sub 2}Cu{sub 3{minus}{ital x}}{ital M}{sub {ital x}}O{sub 7} [Dy-123({ital M})] system. Resistivity and ac susceptibility studies indicate that the {ital T}{sub {ital c}} suppression rate for a given {ital M} ion depends on the ionic radius of the rare earth ({ital R}) and is higher for larger rare earths. The trend in {ital T}{sub {ital c}} suppression as a function of concentration ({ital x}) shows deviation from Abrikosov-Gor{close_quote}kov behavior. A metal-insulator transition is observed at higher dopant concentrations, and the semiconducting phases are found to obey the Mott{close_quote}s variable range hopping mechanism of conduction. The parameters related to hopping conduction; viz., the characteristic temperature ({ital T}{sub 0}), localization length ({ital a}), hopping range ({ital R}), and hop energy ({ital W}) have been calculated, and a comparative study of the variation of these parameters in the two systems has been made. {copyright} {ital 1996 The American Physical Society.}
- OSTI ID:
- 284400
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 21 Vol. 53; ISSN PRBMDO; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BARIUM OXIDES
CRYSTAL STRUCTURE
CUPRATES
D STATES
DYSPROSIUM OXIDES
ELECTRIC CONDUCTIVITY
HIGH-TC SUPERCONDUCTORS
IRON ADDITIONS
LATTICE PARAMETERS
MAGNETIC MOMENTS
NICKEL ADDITIONS
SAMARIUM OXIDES
SUBSTOICHIOMETRY
SUPERCONDUCTIVITY
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0013-0065 K
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
TRANSITION TEMPERATURE
ZINC ADDITIONS